Regulatory approval for Fessenheim 2 upgrades

30 April 2013

French nuclear regulators have prescribed a program of works to be carried out at Fessenheim 2 to allow France's second-oldest nuclear unit to continue to operate beyond its third ten-yearly inspection.

Power reactors in France are required to undergo exhaustive safety reviews every ten years in order to be allowed to continue to operate. The latest ten-yearly review of Fessenheim 2 was conducted between April 2011 and March 2012.

The Autorité de Sûreté Nucléaire (ASN), France's national nuclear regulator, is requiring operator EDF to carry out a range of works at the plant including strengthening of the reactor's concrete basemat to increase its resistance to corium, and the installation of extra emergency cooling. Corium is a mixture of molten cladding, fuel, and structural steel formed in the event of a serious accident involving the melting of fuel in the reactor, which could potentially break through the steel reactor pressure vessel.

Similar work has already been completed at Fessenheim 1, which is of a similar design to unit 2, to the satisfaction of ASN. However, the regulator says it has also called for some further measures specific to unit 2 reflecting the slight differences between the two sister units. The regulator's decision takes into account lessons learned from the Fukushima accident of 2011 and the findings of safety assessments performed at French reactors following on from the accident.

EDF has been given until the end of 2013 to complete the work. In a statement, the company said that some of the work will take place during a scheduled reactor outage in July.

Political threat

Regulatory approval may not be sufficient to ensure the continued operation of the Fessenheim units, which started up in 1977 and 1978 and are France's oldest operating reactors. French president Francois Hollande announced in 2012 that the plant would close by the end of 2016, in fulfilment of promises made during his election campaign, although the closure is not yet enshrined in law. A national period of debate over a potential 'energy transition' is ongoing, with a new energy bill due to be published in June.